Two new studies about anorexia nervosa indicate that the mental disorder may have a physical basis.

Anorexia nervosa is a disease in which persons take in so few calories that they can die of starvation. Females are ten times more likely to develop anorexia than males.

In the first study from the University of Pittsburgh, young women with anorexia showed significantly different activity levels in the brain regions linked to anxiety and perfectionism.

Walter H. Kaye, M.D., professor of psychiatry, and his colleagues performed magnetic resonance imaging (MRIs) of the brains of thirteen women who had recovered from anorexia and maintained healthy weights for at least one year. This group played a game along with members of a control group.

The formerly anorexic players were overly concerned about making mistakes and correcting them, and experienced less immediate pleasure from winning when compared to the control group.

Dr. Kaye said that he hoped this and other research would contribute to better treatment options for anorexia, which has the highest death rate of any mental disorder.

This study appears in the December issue of the American Journal of Psychiatry.

The second study indicates that boys with twin sisters have more risk of developing anorexia.

Dr. Marco Procopio and Paul Marriott examined the records of over 4,000 Swedish twins born between 1935 and 1958. Among male/female twins, females had less risk of developing anorexia than females who had no twins. However, their brothers had the same risk as their sisters.

The authors are not sure if this is caused in utero or as a result of growing up with a female twin.

Their study was published in Archives of General Psychiatry.